I found a little known but very useful and simple sculpting tool by Mikage Boa of
slmame.com. The tool is in Japanese, as is her web site. Thanks to Google translate, I found this to be very simple tool thats also very well designed.

This cute tool lets you build up large blocks into various heights. Each color
represents a different Z-height. Using the tool is simple and direct, just
click and drag colors around to set various heights. Then Click the
File-Save button and upload the sculpt.

This tool is written in Japanese, so here is a translation of the menu to
English:

As an example, here is a X- shaped staircase made with the tool:

The saved Sculpt:

And after uploading it:

The shape for a staircase:

The saved sculpt:

And a nice set of stairs for getting into a building result:

Once you upload the sculpt, change the seam type to 'Cylinder', or drop this
script into the entry state of a empty script in a prim: